Antimicrobial properties of starch films incorporated with chitosan nanoparticles: In vitro and in vivo evaluation

Comparison of Antimicrobial Activity of Chitosan Nanoparticles against Bacteria and Fungi

Chitosan nanoparticles (CSNPs) have attracted wide interest; however, there has been no substantial information about a direct comparison of the antimicrobial activity of CSNPs on bacteria and fungi. Thus, in this study, simple, economically feasible CSNPs were synthesized and assessed for their antimicrobial activity. This investigation indicated that the coordination inducing effect of CSNPs could dissociate the tryptophan (Trp) and tyrosine (Tyr) residue groups on the peptide chain of the bovine serum albumin (BSA) molecule, thereby increasing the absorption intensity. The growth of E. coli and S. aureus could be completely inhibited when the concentration of CSNPs in the solution was higher than 0.6 mg/mL. The CSNPs showed more potent antibacterial activity against Gram-negative bacteria (E. coli) than against Gram-positive bacteria (S. aureus). In addition, the CSNPs were effective at initiating cellular leakage of fungal mycelia and damping off fungal pathogens, and their antifungal effects were stronger on P. steckii than on A. oryzae. Furthermore, the antimicrobial activity of the CSNPs was found to be more effective against bacteria than against fungi. This study thus ascertained the antimicrobial activity of synthesized CSNPs against different microorganisms, as well as their different degrees of inhibition.

Chitosan-based hydrogels to treat hydrofluoric acid burns and prevent infection

There is an urgent need for treatments for hydrofluoric acid (HF) burns and their derivative problems that prevent hydrogen ion dissociation and fluoride ion binding to tissues. This study evaluated the ability of chitosan-based hydrogels combined with a buffer solution containing either boric acid or Tris and calcium gluconate (CHS-BA-CG and CHS-Tris-CG) to repair HF burn wounds and prevent wound infections. We assessed calcium release rates and biocompatability and constructed a mouse HF burn model to assess the tissue repair effects of the hydrogels. Finally, we performed disc diffusion tests from burn tissue and quantified the bacterial counts to assess the anti-infection properties of the hydrogels. Calcium was gradually released in the CHS-BA-CG and CHS-Tris-CG groups (73% and 43%, respectively, after 48 h). The cell viabilities at 48 h after HF burn in these groups were significantly higher than those in the phosphate-buffered saline (PBS) and CG-treated groups. Histopathological evaluation showed a clear boundary between the epidermal and dermal layers in both CHS-BA-CG and CHS-Tris-CG-treated groups, indicating their effectiveness in tissue repair. In the disc diffusion test, CHS-BA-CG and CHS-Tris-CG exhibited larger inhibition zones against Acinetobacter baumannii than those for PBS and CG. The bacterial counts on HF burn wounds were significantly lower in the CHS-BA-CG and CHS-Tris-CG-treated groups than those in the PBS and CG-treated groups. The in vitro studies demonstrated the biocompatibility and antimicrobial effects of the CHS-BA-CG and CHS-Tris-CG hydrogels. Both gels also demonstrated tissue repair and anti-infection effects. Thus, chitosan-based hydrogels may be candidates for HF burn therapy.

Biodegradable Antimicrobial Films for Food Packaging: Effect of Antimicrobials on Degradation

The environmental problem generated by the massive consumption of plastics makes necessary the developing of biodegradable antimicrobial materials that can extend food shelf-life without having a negative impact on the environment. The current situation regarding the availability of biodegradable food packaging materials has been analysed, as well as different studies where antimicrobial compounds have been incorporated into the polymer matrix to control the growth of pathogenic or spoilage bacteria. Thus, the antimicrobial activity of active films based on different biodegradable polymers and antimicrobial compounds has been discussed. Likewise, relevant information on biodegradation studies carried out with different biopolymers in different environments (compost, soil, aquatic), and the effect of some antimicrobials on this behavior, are reviewed. In most of the studies, no relevant effect of the incorporated antimicrobials on the degradation of the polymer were observed, but some antimicrobials can delay the process. The changes in biodegradation pattern due to the presence of the antimicrobial are attributed to its influence on the microorganism population responsible for the process. More studies are required to know the specific influence of the antimicrobial compounds on the biodegradation behavior of polymers in different environments. No studies have been carried out or marine media to this end.

Design and characterization of PANI/starch/Fe2O3 bio composite for wastewater remediation

A new synthesized polyaniline/starch/hematite bio composite (PANI/S/Fe₂O₃ BC) has been studied as an effective material for on-site water remediation. PANI/S/Fe₂O₃ BC was developed by combining the techniques of co-precipitation and interfacial polymerization in the presence of aqueous starch solution in an acidic medium under ultrasonic irradiation. The nano-morphologies and structures of the designed PANI/S/Fe₂O₃ BC were evaluated by various techniques relative to PANI and Fe₂O₃ nanoparticles. In single and multiple systems, PANI/S/Fe₂O₃ BC was evaluated as a possible adsorbent for different heavy metals, including As³⁺, Zn²⁺, and Co²⁺, relative to PANI and Fe₂O₃ nanoparticles. In terms of pH value, operating temperature, initial heavy metal concentration, contact time, adsorbent dose and competitive ions in the solutions, the adsorption process was optimized. For 92% overall adsorption of Co²⁺ and 100% overall adsorption of both As³⁺ and Zn²⁺, the adsorption equilibrium was achieved within 60 and 120 min, respectively. In addition, adsorption thermodynamic analysis shows that the As³⁺ ions adsorption process was not random and the pseudo-second-order fitted with experimental results. Moreover, PANI/S/Fe₂O₃ BC was evaluated as an antibacterial agent against Gram-negative bacteria (Salmonella typhimurium) and Gram-positive bacteria (S. aureus, Methicillin-Resistant Staphylococcus, Aureus Clinical isolate and Bacillus subtilis). The reported performances indicated that the PANI/S/Fe₂O₃ BC is a potent candidate for industrial water bioremediation.

Corn Starch/Chitosan Nanoparticles/Thymol Bio-Nanocomposite Films for Potential Food Packaging Applications

This work aims to develop corn starch/chitosan nanoparticles/thymol (CS/CNP/Thy) bio-nanocomposite films as potential food packaging materials that can enhance the shelf life of food. CS/CNP/Thy bio-nanocomposite films were prepared by the addition of different concentrations of thymol (0, 1.5, 3.0, 4.5 w/w%) using a solvent casting method. The resulting films were characterized in terms of optical, mechanical, and water vapor permeability (WVP) properties. The addition of thymol was found to reduce the tensile strength (TS), elongation at break (EAB), and Young’s modulus (YM) of the films. Generally, the increment in the concentration of thymol did not significantly affect the TS, EAB, and YM values. The addition of 1.5 w/w% thymol increased the WVP of the films but the WVP reduced with the increase in thymol concentrations. CS/CNP/Thy-3% bio-nanocomposite films demonstrated the potential to lengthen the shelf life of cherry tomatoes packed with the films, whereby the cherry tomatoes exhibited no significant changes in firmness and the lowest weight loss. In addition, no mold growth was observed on the sliced cherry tomatoes that were in direct contact with the films during 7 days of storage, proving the promising application of the films as active food packaging materials.

Graphene Derivatives in Biopolymer-Based Composites for Food Packaging Applications

This review aims to showcase the current use of graphene derivatives, graphene-based nanomaterials in particular, in biopolymer-based composites for food packaging applications. A brief introduction regarding the valuable attributes of available and emergent bioplastic materials is made so that their contributions to the packaging field can be understood. Furthermore, their drawbacks are also disclosed to highlight the benefits that graphene derivatives can bring to bio-based formulations, from physicochemical to mechanical, barrier, and functional properties as antioxidant activity or electrical conductivity. The reported improvements in biopolymer-based composites carried out by graphene derivatives in the last three years are discussed, pointing to their potential for innovative food packaging applications such as electrically conductive food packaging.

Polysaccharide and Protein Films with Antimicrobial/Antioxidant Activity in the Food Industry: A Review

From an economic point of view, the spoilage of food products during processing and distribution has a negative impact on the food industry. Lipid oxidation and deterioration caused by the growth of microorganisms are the main problems during storage of food products. In order to reduce losses and extend the shelf-life of food products, the food industry has designed active packaging as an alternative to the traditional type. In the review, the benefits of active packaging materials containing biopolymers (polysaccharides and/or proteins) and active compounds (plant extracts, essential oils, nanofillers, etc.) are highlighted. The antioxidant and antimicrobial activity of this type of film has also been highlighted. In addition, the impact of active packaging on the quality and durability of food products during storage has been described.